Positive Battery Terminal Antenna Ground Plane

ABSTRACT

A positive terminal of a battery may act as an antenna ground plane for communicating battery status information. The positive terminal of the battery may include a first electrically conductive external surface with a first surface area. The negative terminal of the battery may include a second electrically conductive external surface with a second surface area less than the first surface area. An antenna impedance matching circuit may electrically connect to a communication circuit, an antenna, and the positive terminal of the battery. Thus the positive terminal of the battery may act as a ground plane for the antenna.

FIELD OF THE INVENTION

The disclosure generally relates to apparatus and methods to useexternal surfaces of a battery as a ground plane for an antenna in acommunication system and, more particularly, to use a positive terminaland electrically conductive external surface, typically the metalbattery can or casing, of a battery as a ground plane for an antennathat communicates battery status information.

BACKGROUND

On-cell battery fuel gauges may require a user to press two buttons,wait several seconds, and then observe an indication of the state ofcharge of the battery. Such a solution may require removing thebatteries from the device and checking the battery to decide whether itis necessary to replace the battery. As such, solutions that avoidremoval of a battery from a device to check the remaining capacityprovide significant advantages for consumers.

In some embodiments, a battery status may be detected by remoteindication using an analog to digital converter (ADC) and a Near FieldCommunication (NFC) Integrated Circuit (IC) together with a magneticdiverter and a thin foil antenna on the battery label. Applicationsoftware, for example executing on a smart phone, may be used to receivebattery status information remotely. Such battery status information mayinclude the battery voltage that is then used to provide an indicationof battery status to the user.

Conventionally packaged silicon integrated circuits together with theassociated discrete resistors and capacitors when installed, forexample, directly onto the label of the battery cell may increase thediameter of the cell beyond the capabilities of many existing devicecavities. Furthermore, NFC detection range may in some embodiments belimited to several centimeters.

Operation of RF transceivers near metal surfaces may present technicalchallenges, for example with parasitic coupling of the antenna to themetal surfaces. In some embodiments battery cells may be constructedwith a conductive metal can, for example constructed with steel,particularly primary alkaline batteries available to consumers. Thepresence of such metal surfaces near an antenna installed on a wirelesstransmitter circuit may detune the antenna significantly, deterioratingperformance and reducing the usable range to a receiving device.

SUMMARY

One exemplary embodiment includes an apparatus that includes a positiveterminal of a battery having a first electrically conductive externalsurface with a first surface area; a negative terminal of a batteryhaving a second electrically conductive external surface with a secondsurface area; and an antenna impedance matching circuit, electricallyconnected to a communication circuit, an antenna, and the positiveterminal of the battery. The first surface area is greater than thesecond surface area

Another exemplary embodiment includes a method, that includes providinga positive terminal of a battery having a first electrically conductiveexternal surface with a first surface area; providing a negativeterminal of a battery having a second electrically conductive externalsurface with a second surface area less than the first surface area;providing an antenna impedance matching circuit; and electricallyconnecting the antenna impedance matching circuit to the positiveterminal of the battery.

Yet another exemplary embodiment includes a method that includesproviding a negative terminal of a primary alkaline battery with a firstsurface area; providing a positive terminal of a primary alkalinebattery as a ground plane of an antenna, the positive terminalcomprising a second surface area greater than the first surface area;providing an antenna impedance matching circuit; electrically connectingthe antenna impedance matching circuit to the positive terminal of theprimary alkaline battery; electrically connecting the antenna impedancematching circuit to a communication circuit and an antenna; andcalculating data relating to the remaining capacity of the batteryincluding corrections for load on the battery related to transmissionand reception of data using the communication circuit, the antennaimpedance matching circuit, the antenna, and the positive terminal ofthe primary alkaline battery. In such primary alkaline batteries, theanode can comprise zinc and the cathode can comprise manganese oxide. Inyet another optional form, the battery is a primary Zinc-Carbon battery,the battery comprising an anode, a cathode, and an electrolyte. Inaddition to being a primary battery such as a primary alkaline batteryor a primary Zinc-Carbon battery, the battery may be a primary lithiumbattery. Alternatively, the battery can be a secondary battery, forexample, a secondary battery such as a nickel metal hydride (NiMH)battery, a nickel cadmium (NiCad) battery, a silver/zinc battery, anickel/zinc battery, or a lithium solid state rechargeable battery. Forrechargeable chemistries, the terminals of the battery switch duringcharging or discharging. Generally, any battery chemistry may be used inaccordance with the disclosure provided that the electrically conductivemetal battery can is electrically connected to the positive terminal.

In accordance with the teachings of the disclosure, any one or more ofthe foregoing aspects of an apparatus or a method may further includeany one or more of the following optional forms.

In one optional form, the first electrically conductive external surfaceelectrically connects to a cathode of a primary alkaline battery, andthe second electrically conductive external surface electricallyconnects to an anode of a primary alkaline battery.

In another optional form, a ground plane of the communication circuitelectrically connects to the negative terminal of the battery.

In yet another optional form, the antenna impedance matching circuitcomprises a balun configured to convert, for a first communicationfrequency, an input impedance of the impedance matching circuit to anoutput impedance of the impedance matching circuit.

In still another optional form an electrical length of the firstelectrically conductive external surface is greater than 0.25 of awavelength of a signal transmitted by the communication circuit into theantenna impedance matching circuit, and the electrical length of thefirst electrically conductive external surface is a physical length ofthe first electrically conductive external surface multiplied by theratio of (i) the propagation time of the signal through the firstelectrically conductive external surface to (ii) the propagation time ofthe signal in free space over a distance equal to the physical length ofthe first electrically conductive external surface.

In still another optional form, the electrical length of the firstelectrically conductive external surface is configured to minimize areflected power from the antenna back into the antenna impedancematching circuit as a result of the communication circuit transmittingthe signal.

In still another optional form, the antenna impedance matching circuitcomprises at least one of (i) a capacitor and (ii) an inductor, and atleast one of (i) the capacitor and (ii) the inductor are electricallyconnected between the communication circuit and the positive terminal ofthe battery.

In still another optional form, the battery is a primary alkalinebattery, the battery comprising an anode, a cathode, and an alkalineelectrolyte. In such primary alkaline batteries, the anode can comprisezinc and the cathode can comprise manganese oxide. In yet anotheroptional form, the battery is a primary Zinc-Carbon battery, the batterycomprising an anode, a cathode, and an electrolyte. In addition to beinga primary battery such as a primary alkaline battery or a primaryZinc-Carbon battery, the battery may be a primary lithium battery.Alternatively, the battery can be a secondary battery, for example, asecondary battery such as a nickel metal hydride (NiMH) battery, anickel cadmium (NiCad) battery, a silver/zinc battery, a nickel/zincbattery, a lithium-ion or a lithium solid state rechargeable battery.Generally, any battery chemistry may be used in accordance with thedisclosure provided that the exterior metal battery can is electricallyconnected to the positive terminal.

In still another optional form, the balun comprises a first winding anda second winding around a magnetic ferrite, a first end of the firstwinding is electrically connected to the antenna, and a second end ofthe first winding is electrically connected to the positive terminal ofthe battery.

In still another optional form, a first end of the second winding iselectrically connected to the communication circuit, and a second end ofthe second winding is electrically connected to the antenna.

Another optional form includes electrically connecting the antennaimpedance matching circuit to a communication circuit and an antenna.

Yet another optional form includes electrically connecting a groundplane of the communication circuit to the negative terminal of thebattery.

Still another optional form includes providing a balun configured toconvert an input impedance encountered by a signal transmitted by thecommunication circuit into the impedance matching circuit to an outputimpedance.

Still another optional form includes providing the first electricallyconductive external surface with an electrical length greater than 0.25of a wavelength of a signal transmitted by the communication circuitinto the antenna impedance matching circuit.

Still another optional form includes providing the first electricallyconductive external surface with an electrical length that minimizes areflected power from the antenna back into the antenna impedancematching circuit as a result of the communication circuit transmittingthe signal.

Still another optional form includes providing the antenna impedancematching circuit with at least one of (i) a capacitor and (ii) aninductor, and electrically connecting at least one of (i) the capacitorand (ii) the inductor between a communication circuit and the positiveterminal of the battery.

Still another optional form includes providing a primary alkalinebattery comprising an anode, a cathode, and an alkaline electrolyte;electrically connecting the cathode of the battery to the firstelectrically conductive external surface of a battery; and electricallyconnecting the anode of the battery to the second electricallyconductive external surface of a battery. In such primary alkalinebatteries, the anode can comprise zinc and the cathode can comprisemanganese oxide. In addition to being a primary battery such as aprimary alkaline battery, the battery may be a primary lithium battery.Alternatively, the battery can be a secondary battery, for example, asecondary battery such as a nickel metal hydride (NiMH) battery, anickel cadmium (NiCad) battery, a silver/zinc battery, a nickel/zincbattery, or a lithium ion, lithium polymer or a lithium solid staterechargeable battery. Generally, any battery chemistry may be used inaccordance with the disclosure provided that the exterior metal batterycan is electrically connected to the positive terminal.

Still another optional form includes providing a balun comprising afirst winding and a second winding around a magnetic ferrite such thatan output impedance of the balun approximates an input impedance of theantenna; electrically connecting a first end of the first winding to theantenna; and electrically connecting a second end of the first windingto the positive terminal of the battery.

Still another optional form includes electrically connecting a first endof the second winding to the communication circuit; and electricallyconnecting a second end of the second winding to the antenna.

Exemplary embodiments may include computer-implemented methods that may,in other embodiments, include apparatus configured to implement themethod, and/or non-transitory computer readable mediums comprisingcomputer-executable instructions that cause a processor to perform themethod.

Advantages will become more apparent to those skilled in the art fromthe following description of the preferred embodiments which have beenshown and described by way of illustration. As will be realized, thepresent embodiments may be capable of other and different embodiments,and their details are capable of modification in various respects.Accordingly, the drawings and description are to be regarded asillustrative in nature and not as restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

The Figures described below depict various aspects of the system andmethods disclosed herein. Each figure depicts a particular aspect of thedisclosed system and methods, and each of the figures is intended toaccord with a possible aspect thereof. Further, wherever possible, thefollowing description refers to the reference numerals included in thefollowing figures, in which features depicted in multiple figures aredesignated with consistent reference numerals.

There are shown in the Figures arrangements which are presentlydiscussed, it being understood, however, that the present embodimentsare not limited to the precise arrangements and instrumentalities shown,wherein:

FIG. 1 illustrates an exemplary consumer alkaline battery with aninstalled printed circuit board to transmit battery status information,in accordance with one aspect of the present disclosure;

FIG. 2 illustrates an exemplary block diagram of an apparatus to detecta voltage of a battery, and communicate battery status information overan antenna, in which an anode is used as a ground plane;

FIG. 3 illustrates an exemplary block diagram of an apparatus to use acathode of an alkaline battery as a ground plane for an antenna,including a capacitor/inductor based impedance matching circuit, inaccordance with one aspect of the present disclosure;

FIG. 4 illustrates an exemplary block diagram of an apparatus to use acathode of an alkaline battery as a ground plane for an antenna,including a balun based impedance matching circuit, in accordance withone aspect of the present disclosure;

FIG. 5 illustrates an exemplary received signal strength indication(RSSI) plot over a variety of samples including an anode ground planeand a cathode ground plane, in accordance with one aspect of the presentdisclosure;

FIG. 6 illustrates an exemplary RSSI polar plot for a horizontalorientation of a receiver relative to an anode ground plane and acathode ground plane, in accordance with one aspect of the presentdisclosure;

FIG. 7 illustrates an exemplary RSSI polar plot for a verticalorientation of a receiver relative to an anode ground plane and acathode ground plane, in accordance with one aspect of the presentdisclosure; and

FIG. 8 illustrates an exemplary block diagram of a method toelectrically connect an antenna impedance matching circuit to anexternal surface of a battery.

The Figures depict preferred embodiments for purposes of illustrationonly. Alternative embodiments of the systems and methods illustratedherein may be employed without departing from the principles of theinvention described herein.

DETAILED DESCRIPTION

Although the following text sets forth a detailed description ofnumerous different embodiments, it should be understood that the legalscope of the description is defined by the words of the claims set forthat the end of this patent and equivalents. The detailed description isto be construed as exemplary only and does not describe every possibleembodiment since describing every possible embodiment would beimpractical. Numerous alternative embodiments may be implemented, usingeither current technology or technology developed after the filing dateof this patent, which would still fall within the scope of the claims.

One embodiment of the present disclosure includes enabling an RFwireless sensor to operate on a battery with positive-biased case, orcan, to improve the range, or maximum reading distance, between thetransmitter installed on the battery and the reader. The reader mayinclude a smart phone, tablet, local network hub, or another embodimentof a computing device.

FIG. 1 illustrates an exemplary apparatus 100 including a consumeralkaline battery 110, and an installed printed circuit board 120 thatincludes a variety of interconnected components that transmit a statusof a battery. The printed circuit board 120 may be electricallyconnected to the cathode of the battery 130, and the anode of thebattery 140, for example by making a low-impedance connection throughwires, clips, or otherwise. Consumer alkaline batteries 110, inparticular, may benefit from the installed printed circuit board 120because alkaline batteries often require replacement in consumerelectronic devices and trips to a retailer to purchase new batteries,and as such battery status information is particularly relevant.

The active material of the anode may comprise zinc. The active materialof the cathode may comprise a composition comprising manganese oxideand/or manganese dioxide. Manganese dioxide may comprise gamma manganesedioxide, lambda manganese dioxide, or combinations thereof. Manganesedioxide may be prepared electrolytically as electrolytic manganesedioxide (EMD) or chemically as chemical manganese dioxide (CMD).Manganese dioxide is also available as natural manganese dioxide (NMD),however, NMD typically is not employed in alkaline batteries. Mixturesof more than one of EMD, CMD, and NMD may be used. Accordingly, as usedherein, manganese dioxide refers to EMD, CMD, NMD and combinationsthereof.

Active material compositions for cathodes comprising manganese dioxidemay contain at least about 91 percent by weight (e.g., impurities suchas sulfate salts, various metals and the like are present in an amountno greater than 9% by weight). Commercially available EMD is provided asa composition comprising a high purity, high density, gamma manganesedioxide, and is desirable as a cathode active material for alkalinecells. CMD has also been used as electrochemically active cathodematerial in electrochemical cells including alkaline cells andheavy-duty cells; however, commercial chemical processes yield highpurity MnO₂ but do not yield densities of MnO₂ comparable to that ofEMD. As a result EMD has become the most widely used form of batterygrade MnO₂, particularly for alkaline and lithium cells, since in suchapplication it has become most desirable to employ high density MnO₂ toincrease the capacity of these cells.

EMD is typically manufactured from direct electrolysis of a bath ofmanganese sulfate and sulfuric acid. Battery grade CMD may be producedvia the “Sedema process,” by employing the reaction mixture of MnSO₄ andan alkali metal chlorate, preferably NaClO₃, as disclosed by U.S. Pat.No. 2,956,860 (Welsh). Distributors of manganese dioxides includeTronox, Erachem, Tosoh, Delta Manganese, and Xiangtan.

Conventional battery grade manganese dioxide-containing compositions donot have a true stoichiometric formula MnO₂, but are better representedby the formula MnOx, wherein x is typically between about 1.92 to 1.96,corresponding to a manganese valence of between about 3.84 and 3.92.Conventional EMD may typically have a value for x of about 1.95 or 1.96,corresponding to a manganese valence of 3.90 and 3.92, respectively.Conventional EMD also has a real density of between about 4.4 and 4.6g/cm3.

In other embodiments of the present disclosure, the printed circuitboard 120 installed on other primary batteries or secondary batteries,for example, a primary lithium-ion battery, or a secondary battery suchas a nickel metal hydride (NiMH) battery, a nickel cadmium (NiCad)battery, a silver/zinc battery, a nickel/zinc battery, or a lithiumsolid state rechargeable battery. For rechargeable chemistries, theterminals of the battery switch during charging or discharging.Regardless, in a secondary rechargeable battery, the electricallyconductive external surface of the battery comprises the positiveterminal while discharging and being used to power a device.

FIG. 2 illustrates a block diagram of an exemplary apparatus 200 todetect and transmit battery status information. The apparatus 200includes a battery 210, with an anode of the battery electricallyconnected to a ground 215, and a cathode of the battery electricallyconnected to an input of a voltage regulator 220. In some embodiments,the voltage regulator 220 may step-up a single alkaline cell voltage toa suitable voltage to power a communications circuit 230, for example to2.4 volts or 3 volts. The voltage regulator 220 may be electricallyconnected to a ground 225 with a low impedance electrical path to theground 215 and the anode of the battery 210. In some embodiments, thevoltage of the battery cell may be offset at the input of an analog todigital converter (ADC) to effectively improve the resolution of theADC.

In some embodiments, the communications circuit 230 may include a groundplane with a low impedance path to a ground 235. The ground 235 mayshare a low impedance path with voltage regulator ground 225, and theanode of the battery ground 215 to provide an appropriate electricalreference for proper functioning of the ADC disposed within thecommunications circuit 230. In some embodiments, a ground plane of thedigital circuitry of the communications circuit 230 may be electricallyisolated with a relatively high impedance from a ground plane of theradio frequency transmission circuitry.

A transmitter disposed within the communications circuit 230 may includea balanced connection to an impedance matching circuit 240. In otherembodiments, the connection between the communications circuit 230 andthe impedance matching circuit 240 may include an unbalanced connection,with an impedance of 50 ohms, or otherwise as a characteristic inputimpedance to the impedance matching circuit 240.

The impedance matching circuit 240 is configured to convert an inputimpedance encountered by the communications circuit 230 to an outputimpedance for a particular frequency, using a variety of passive andactive electrical components. The output impedance of the impedancematching circuit 240 may approximate the characteristic input impedanceof an antenna 250 and any associated wiring or electrical connections.In other embodiments, the impedance matching circuit may be configuredto minimize a reflected power from the antenna 250 as a result of asignal transmitted at a particular frequency, or set of frequencies,from the communications circuit.

Embodiments of the impedance matching circuit 240 may include one or aplurality of connections to a ground 245. The ground 245 may include alow impedance path to the grounds 235, 225, and 215 of the remainder ofthe apparatus 200. In some embodiments, the ground 245 of the impedancematching circuit 240 may include a ground plane of the antenna 250. Inother embodiments the ground plane of the antenna 250 may include theanode of the battery 210 and an electrical length of the anode of thebattery 210 may be significantly less than 0.25 the wavelength of asignal transmitted by the communications circuit 230 into the impedancematching circuit 240.

In another embodiment, the transmitter installed on the battery mayinclude a Bluetooth® Low Energy wireless sensor, for example based onthe Texas Instruments CC2540 integrated circuit. In other embodiments,the transmitter may include a UHF transceiver for exchanging data overshort distances. The transmitter may include a voltage booster, orvoltage regulator to increase the voltage of the single alkaline cell.Such an embodiment may include a printed circuit board installed inproximity to the battery 210, due to space constraints in the batterycavity of most devices. Attachment springs may provide battery anelectrical connection to allow an electrical potential for measurementand also power supply to the communications circuit 230.

Proximity of metal to the antenna 250 may detune the antenna 250 awayfrom a frequency range of interest and negatively affect signaltransmission and reception. As the distance between the sensor and thebattery 210 is reduced, due to space constraints, the detuning effectbecomes more pronounced. When an optimum tuned transmitter functionsnear a metal object, for example near the battery 210, the RFtransceiver may be grounded to the positive power supply rail, or thecathode of the battery 210, to make use of the relatively larger cathodeterminal, or battery case, as a more effective ground plane. In thiscase other metal objects, such as additional battery cells and metalparts of the device near the monitored battery, may not interferesubstantially with the tuned system of antenna and battery.

Positive Terminal of a Battery as Ground Plane

One exemplary embodiment of the present disclosure includes a universalreusable battery remote indication system that includes one or moresilicon integrated circuits that contain an analog to digital converter(ADC) and a communications circuit such as Bluetooth® Low Energytransceiver, Ultra High Frequency (UHF) passive or active RadioFrequency Identification (RFID), WiFi, Zigbee or other means of RFcommunications, an antenna and resistors and/or capacitors and othercomponents that may be needed for the operation of the system.

Snap-on attachment of the indication system to the battery causes anelectrical connection to the battery terminals, or flexible connectionscan also be used. Options may include double-sided flexible PrintedCircuit Boards (PCBs) inserted between the battery and the devicebattery contact and electrically connected between the two sides, orflexible wires with conductive magnets to attach to the device batteryterminals.

A battery indicator may connect to and communicate with a reader orreceiver, to include a smart phone or other BLE, RFID, UHF, WiFi orsimilar enabled communication device. A software application executingon the reader may display the battery status, for example voltage,impedance, load, distance, temperature, time or other parameters. Thesoftware application may interpret these parameters to provide a user ofthe application an indication of battery status and/or a recommendationof when to replace or recharge the battery.

One embodiment of the present disclosure includes a single-cell BLEMonitor (Bluetooth® Low-Energy also known as Bluetooth® 4.xx or “Smart”)wherein the electronics are integrated in an ASIC (Application SpecificIntegrated Circuit) with common ground (DC/DC, ADC and RF) connected tothe positive power supply rail or cathode of the battery. The antennamay be placed on the outer side of the sensor PCB (printed orintegrated) and may be tuned to a fixed position versus the batterycell, which may be at a distance one PCB thickness plus the batterylabel thickness. An incorporated voltage boost converter may enableoperation down to 0.8V-0.9V. The board may include two snap-on batteryattachments that provide power and voltage measurement connectionsbetween battery and sensor. The sensor may attach to a single batterycell and may be placed in a device in non-interfering way between theother battery cells. The assembly may rotate to the most suitableposition, depending on the battery compartment specifics. The batteryattachment may, in some embodiments, be customized to a specific batterytype.

The BLE battery monitor may be read wirelessly, using a BLE enabledsmart phone with an integrated reader software application. The readersoftware application may display distance to the devices, assisting theuser to locate the devices by moving and watching the RF signal strengthincreasing (indicating closer) or decreasing (indicating further).

The functionality of the Reusable Wireless Battery Monitor may not belimited to indication of battery state of charge and distance to thedevice. The BLE module may include a built-in MCU that can be programmedto a variety of additional functions, such as battery impedance orinternal resistance measurement (state of health), temperature,pressure, leakage, safety and low-battery alerts, charge control, powermanagement functions, or other battery related characteristics.

FIG. 3 illustrates one exemplary embodiment of the present disclosurethat includes a block diagram of an apparatus 300. The apparatus 300includes a battery 310 with a negative terminal of the batteryelectrically connected with a low impedance to a ground 360. A positiveterminal of the battery 310 may be electrically connected with a lowimpedance to a voltage regulator 320 and one or more ground connectionsof an impedance matching circuit 340.

The impedance matching circuit 340, as illustrated may include a varietyof passive electrical components, such as capacitors, resistors, andinductors, that together are configured to convert an input impedance ofthe impedance matching circuit 340 to an output impedance of theimpedance matching circuit 340. In some embodiments, such as illustratedin FIG. 3, the input to the impedance matching circuit 340 may include abalanced differential pair of conductors, and the output includes anunbalanced output and variety of a ground connections. However, otheralternative embodiments may include unbalanced inputs, balanced outputs,or other combinations therein.

The communications circuit 330 may include one or more analog to digitalconverters (ADCs) to receive an electrical potential from the battery310 and convert the analog potential to a digital signal fortransmission. In other embodiments, the communications circuit mayconvert the analog potential from the battery 310 to directly modulatean RF signal without an ADC to modulate an RF signal solely with theelectric potential, or current provided by the cell of the battery 310.In some embodiments, the communications circuit 330 may share a lowimpedance ground connection 360 with the anode of the battery 310.

The impedance matching circuit 340 may electrically connect to anantenna 350, as illustrated with an unbalanced connection, for examplewith a 50 ohm impedance. Such embodiments may include antennas 350 thatrequire an effective ground plane to radiate RF energy in a relativelyomnidirectional pattern and prevent reflected power back into thecommunications circuit 330 or impedance matching circuit 340. Asillustrated in FIG. 3, by connecting the ground connections of theimpedance matching circuit 340 to the cathode of the battery 310, thecathode of the battery 310 may act as a ground plane of the antenna 350.In the embodiment wherein the battery 310 is a consumer alkalinebattery, the cathode of the battery 310 may comprise a majority of theexternal surface area of the battery and provide an electrical lengthgreater than 0.25 of the wavelength of transmitted signal from thecommunications circuit 330 into the impedance matching circuit 340.

One implementation of the embodiment illustrated in FIG. 3 may includethe apparatus 300 integrated into a flexible assembly in a manner thatit does not interfere with an available battery cavity. Such anembodiment may be applied to, for example, a AA, AAA, C, or D batterytypes without further modifications. In order to effectively utilize thealkaline battery case or positive terminal as a ground plane, a BLETransceiver antenna impedance matching circuit may be grounded to thepositive power supply rail, or the grounded ends of inductors andcapacitors within the impedance matching circuit. To effectivelyfunction otherwise, the remainder of the apparatus may be grounded tothe negative power supply rail, or anode of the battery. In such anembodiment, the detuning caused by proximity to the battery's metal caseis eliminated.

Alternatively, as illustrated in the exemplary embodiment of FIG. 4, anoutput impedance matching balun, which may also be a DC blockingcomponent, can be grounded to the positive battery can. FIG. 4illustrates a block diagram of an apparatus 400 that includes a battery410, likewise with the cathode of the battery 410 electrically connectedto a voltage regulator 420 and the anode of the battery 410 electricallyconnected to a ground 460. The voltage regulator functions in a similarway as the embodiment of FIG. 3, together with the communicationscircuit 430 to communicate a status of the battery 410. Likewise, thecommunications circuit 430 may share a ground connection 460 with theanode of the battery to function effectively.

However, the embodiment illustrated in FIG. 4 includes an impedancematching circuit 440 that includes a balun 445 that converts a balancedsignal from the communications circuit 430 to an unbalanced signal foran antenna 450. The negative end of the unbalanced end of the balun 445may be electrically connected to the cathode of the battery toeffectively use the cathode of the battery as a ground plane for theantenna 450.

In one particular embodiment, the balun 445 may include a balanced andunbalanced windings around a magnetic ferrite, configured as necessaryto convert a balanced input impedance to an unbalanced output impedance.As illustrated in FIG. 4, both ends of the balanced connection may beelectrically connected to the communications circuit 430, one end of theunbalanced winding electrically connected to the antenna 450, and oneend of the unbalanced winding electrically connected to the cathode ofthe battery.

By using the battery connections as illustrated in FIG. 4, the sensormodule and hence the antenna, which are, for example, printed on anouter side of the PCB or surface-mounted chip antenna, may remain at afixed small distance from the metal battery can or cathode of thebattery 410 and the balun 445 may be tuned specifically for thatdistance. In one specific embodiment, the battery length (e.g., 50 mmfor AA and 45 mm for AAA sizes respectively) may approximate a halfwavelength (e.g., 61.2 mm) of a center 2.45 GHz carrier frequency andmay form an effective ground plane for the antenna 450.

Signal Reception Improvements with Positive Terminal Antenna GroundPlane

FIG. 5 illustrates a received signal strength indication (RSSI) graph500 that represents the received signal strength 520 from a BluetoothLow-Energy sensor mounted on a Duracell alkaline AA battery, measuredwith an iPhone 6 at 20 feet away using a Texas Instruments “Sensor Tag”app for a variety of samples 510 plotted using the negative terminal asa ground plane 530, as compared with the positive terminal as the groundplane 540.

In one embodiment, the received RF power, using the cathode as theground plane approximates at −85 decibels over one milliwatt (dBm),compared to −95 dBm when using the anode of the battery as a groundplane. The received signal strength may determine if communications willbe established and if data packets are successfully exchanged betweenthe sensor and the reader, for example between the battery and the smartphone. Stronger signals result in a better range, or maximum distance,between the sensor and the reader, or alternatively lower powerconsumption of the sensor for the same distance. For example, theaverage current drain of the sensor may be limited to about 10microamps, if several years of service life are desired withoutsignificant reduction of battery life. The difference illustrated inFIG. 5 of approximately 10 dBm shown may result in approximately 10times lower RF power for the sensor with cathode ground plane for theantenna. Active RF transmission and/or reception may represents theheaviest load on the battery and may factor in battery lifecalculations. As such, corrections for such load during transmissionand/or reception may be accounted for during calculation of remainingbattery capacity.

Directionality of Signal Reception with Positive Terminal Antenna GroundPlane

FIGS. 6 and 7 illustrate polar RSSI plots for a horizontal orientation600 and vertical orientation 700 with the results of further testingperformed with two AA alkaline cells side by side and the voltage sensorboard mounted on one of them. The device was rotated for each of thehorizontal and vertical orientation in four relative directions, 0degrees for axis 610 and 710, 90 degrees for axes 620 and 720, 180degrees for axes 630 and 730, and 270 degrees for axes 640 and 740. Theaverages of the RSSI were taken from 60 points for each direction over 1minute period (one sample per second).

As illustrated in FIGS. 6 and 7, the test results show consistentsignificant advantage of the cathode, or positive terminal ground plane,as indicated by plot 660 and 760, versus the anode, or negative terminalground plane, as indicated by plot 650 and 750. The advantage ofpositive terminal grounding was further confirmed with other devices andmetal objects in proximity to the sensor.

Fabrication and Use of Positive Terminal Antenna Ground Plane

FIG. 8 illustrates a block diagram 800 that represents one embodiment ofa method to fabricate and/or use the positive terminal of a battery asan antenna ground plane. For example, the block diagram 800 includesproviding a positive terminal of a battery having a first electricallyconductive external surface with a first surface area (block 805).Furthermore, the block diagram 800 includes providing a negativeterminal of a battery having a second electrically conductive externalsurface with a second surface area less than the first surface area(block 815). By providing an antenna impedance matching circuit (block830) the antenna impedance matching circuit may be electricallyconnected to the positive terminal of the battery (block 845).

Other embodiments include electrically connecting the antenna impedancematching circuit to a communication circuit and an antenna. Furthermore,alternative embodiments include electrically connecting a ground planeof the communication circuit to the negative terminal of the battery.Still further, alternative embodiments include providing a balunconfigured to convert an input impedance encountered by a signaltransmitted by the communication circuit into the impedance matchingcircuit to an output impedance. Other embodiments include providing thefirst electrically conductive external surface of the battery with anelectrical length greater than 0.25 of a wavelength of a signaltransmitted by the communication circuit into the antenna impedancematching circuit.

Alternative embodiments include providing the first electricallyconductive external surface of the battery with an electrical lengththat minimizes a reflected power from the antenna back into the antennaimpedance matching circuit as a result of the communication circuittransmitting the signal. Still further, embodiments include providingthe antenna impedance matching circuit with at least one of (i) acapacitor and (ii) an inductor, and electrically connecting at least oneof (i) the capacitor and (ii) the inductor between a communicationcircuit and the positive terminal of the battery.

Other alternative embodiments include providing an alkaline primarybattery comprising an anode, a cathode, and an alkaline electrolyte;electrically connecting the cathode of the battery to the firstelectrically conductive external surface of a battery; and electricallyconnecting the anode of the battery to the second electricallyconductive external surface of a battery. Still further, embodimentsinclude providing a balun comprising a first winding and a secondwinding around a magnetic ferrite such that an output impedance of thebalun approximates an input impedance of the antenna; electricallyconnecting a first end of the first winding to the antenna; andelectrically connecting a second end of the first winding to the firstelectrically conductive external surface of the battery.

Yet another embodiment includes electrically connecting a first end ofthe second winding to the communication circuit; and electricallyconnecting a second end of the second winding to the antenna.

Alternative Embodiments

In one embodiment the RF antenna may be kept at a fixed distance fromthe battery case to form a tuned radiator with the battery can as aground plane. The circuit board may be protected by an enclosure in theform of a triangular or trapezoid prism or other shape for a better fitbetween two of the round cylindrical battery cells, and to assureconsistent antenna location.

In other embodiments the antenna impedance matching components may beswitched from negative to positive ground to effectively turn thebattery can into a ground plane.

In still other alternative embodiments, a 2.45 GHz Impedance MatchedBalun, such as the BPF P/N2450BM15A0002 from High Frequency RFSolutions, may be grounded to the battery case (the positive powersupply rail) instead of the common negative ground. As a DC block maynot be required for the balun grounding, its function may not beaffected by the change in balun grounding. The antenna and the alkalinebattery case as a ground plane in such an embodiment may form an optimumRF radiator. The sensor module may in some embodiments be permanentlyattached internally in the battery-powered device.

Additional Considerations

All of the foregoing computer systems may include additional, less, oralternate functionality, including that discussed herein. All of thecomputer-implemented methods may include additional, less, or alternateactions, including those discussed herein, and may be implemented viaone or more local or remote processors and/or transceivers, and/or viacomputer-executable instructions stored on computer-readable media ormedium.

The processors, transceivers, mobile devices, service terminals,servers, remote servers, database servers, heuristic servers,transaction servers, and/or other computing devices discussed herein maycommunicate with each via wireless communication networks or electroniccommunication networks. For instance, the communication betweencomputing devices may be wireless communication or data transmissionover one or more radio links, or wireless or digital communicationchannels.

Customers may opt into a program that allows them share mobile deviceand/or customer, with their permission or affirmative consent, with aservice provider remote server. In return, the service provider remoteserver may provide the functionality discussed herein, includingsecurity, fraud, or other monitoring, and generate recommendations tothe customer and/or generate alerts for the customers in response toabnormal activity being detected.

The following additional considerations apply to the foregoingdiscussion. Throughout this specification, plural instances mayimplement components, operations, or structures described as a singleinstance. Although individual operations of one or more methods areillustrated and described as separate operations, one or more of theindividual operations may be performed concurrently, and nothingrequires that the operations be performed in the order illustrated.Structures and functionality presented as separate components in exampleconfigurations may be implemented as a combined structure or component.Similarly, structures and functionality presented as a single componentmay be implemented as separate components. These and other variations,modifications, additions, and improvements fall within the scope of thesubject matter herein.

Additionally, certain embodiments are described herein as includinglogic or a number of routines, subroutines, applications, orinstructions. These may constitute either software (e.g., code embodiedon a machine-readable medium or in a transmission signal) or hardware.In hardware, the routines, etc., are tangible units capable ofperforming certain operations and may be configured or arranged in acertain manner. In example embodiments, one or more computer systems(e.g., a standalone, client or server computer system) or one or morehardware modules of a computer system (e.g., a processor or a group ofprocessors) may be configured by software (e.g., an application orapplication portion) as a hardware module that operates to performcertain operations as described herein.

In various embodiments, a hardware module may be implementedmechanically or electronically. For example, a hardware module maycomprise dedicated circuitry or logic that is permanently configured(e.g., as a special-purpose processor, such as a field programmable gatearray (FPGA) or an application-specific integrated circuit (ASIC)) toperform certain operations. A hardware module may also compriseprogrammable logic or circuitry (e.g., as encompassed within ageneral-purpose processor or other programmable processor) that istemporarily configured by software to perform certain operations. Itwill be appreciated that the decision to implement a hardware modulemechanically, in dedicated and permanently configured circuitry, or intemporarily configured circuitry (e.g., configured by software) may bedriven by cost and time considerations.

Accordingly, the term “hardware module” should be understood toencompass a tangible entity, be that an entity that is physicallyconstructed, permanently configured (e.g., hardwired), or temporarilyconfigured (e.g., programmed) to operate in a certain manner or toperform certain operations described herein. Considering embodiments inwhich hardware modules are temporarily configured (e.g., programmed),each of the hardware modules need not be configured or instantiated atany one instance in time. For example, where the hardware modulescomprise a general-purpose processor configured using software, thegeneral-purpose processor may be configured as respective differenthardware modules at different times. Software may accordingly configurea processor, for example, to constitute a particular hardware module atone instance of time and to constitute a different hardware module at adifferent instance of time.

Hardware modules may provide information to, and receive informationfrom, other hardware modules. Accordingly, the described hardwaremodules may be regarded as being communicatively coupled. Where multipleof such hardware modules exist contemporaneously, communications may beachieved through signal transmission (e.g., over appropriate circuitsand buses) that connect the hardware modules. In embodiments in whichmultiple hardware modules are configured or instantiated at differenttimes, communications between such hardware modules may be achieved, forexample, through the storage and retrieval of information in memorystructures to which the multiple hardware modules have access. Forexample, one hardware module may perform an operation and store theoutput of that operation in a memory device to which it iscommunicatively coupled. A further hardware module may then, at a latertime, access the memory device to retrieve and process the storedoutput. Hardware modules may also initiate communications with input oroutput devices, and may operate on a resource (e.g., a collection ofinformation).

The various operations of example methods described herein may beperformed, at least partially, by one or more processors that aretemporarily configured (e.g., by software) or permanently configured toperform the relevant operations. Whether temporarily or permanentlyconfigured, such processors may constitute processor-implemented modulesthat operate to perform one or more operations or functions. The modulesreferred to herein may, in some example embodiments, compriseprocessor-implemented modules.

Similarly, the methods or routines described herein may be at leastpartially processor-implemented. For example, at least some of theoperations of a method may be performed by one or more processors orprocessor-implemented hardware modules. The performance of certain ofthe operations may be distributed among the one or more processors, notonly residing within a single machine, but deployed across a number ofmachines. In some example embodiments, the processor or processors maybe located in a single location (e.g., within a home environment, anoffice environment or as a server farm), while in other embodiments theprocessors may be distributed across a number of locations.

The performance of certain of the operations may be distributed amongthe one or more processors, not only residing within a single machine,but deployed across a number of machines. In some example embodiments,the one or more processors or processor-implemented modules may belocated in a single geographic location (e.g., within a homeenvironment, an office environment, or a server farm). In other exampleembodiments, the one or more processors or processor-implemented modulesmay be distributed across a number of geographic locations.

Unless specifically stated otherwise, discussions herein using wordssuch as “processing,” “computing,” “calculating,” “determining,”“presenting,” “displaying,” or the like may refer to actions orprocesses of a machine (e.g., a computer) that manipulates or transformsdata represented as physical (e.g., electronic, magnetic, or optical)quantities within one or more memories (e.g., volatile memory,non-volatile memory, or a combination thereof), registers, or othermachine components that receive, store, transmit, or displayinformation.

As used herein any reference to “one embodiment” or “an embodiment”means that a particular element, feature, structure, or characteristicdescribed in connection with the embodiment is included in at least oneembodiment. The appearances of the phrase “in one embodiment” in variousplaces in the specification are not necessarily all referring to thesame embodiment.

Some embodiments may be described using the expression “coupled” and“connected” along with their derivatives. For example, some embodimentsmay be described using the term “coupled” to indicate that two or moreelements are in direct physical or electrical contact. The term“coupled,” however, may also mean that two or more elements are not indirect contact with each other, but yet still co-operate or interactwith each other. The embodiments are not limited in this context.

As used herein, the terms “comprises,” “comprising,” “includes,”“including,” “has,” “having” or any other variation thereof, areintended to cover a non-exclusive inclusion. For example, a process,method, article, or apparatus that comprises a list of elements is notnecessarily limited to only those elements but may include otherelements not expressly listed or inherent to such process, method,article, or apparatus. Further, unless expressly stated to the contrary,“or” refers to an inclusive or and not to an exclusive or. For example,a condition A or B is satisfied by any one of the following: A is true(or present) and B is false (or not present), A is false (or notpresent) and B is true (or present), and both A and B are true (orpresent).

In addition, use of the “a” or “an” are employed to describe elementsand components of the embodiments herein. This is done merely forconvenience and to give a general sense of the description. Thisdescription, and the claims that follow, should be read to include oneor at least one and the singular also includes the plural unless it isobvious that it is meant otherwise.

The patent claims at the end of this patent application are not intendedto be construed under 35 U.S.C. § 112(f) unless traditionalmeans-plus-function language is expressly recited, such as “means for”or “step for” language being explicitly recited in the claim(s).

The systems and methods described herein are directed to improvements tocomputer functionality, and improve the functioning of conventionalcomputers.

This detailed description is to be construed as exemplary only and doesnot describe every possible embodiment, as describing every possibleembodiment would be impractical, if not impossible. One may be implementnumerous alternate embodiments, using either current technology ortechnology developed after the filing date of this application.

What is claimed is:
 1. An apparatus, comprising: a positive terminal ofa battery, comprising a first electrically conductive external surfacewith a first surface area; a negative terminal of a battery, comprisinga second electrically conductive external surface with a second surfacearea; an antenna impedance matching circuit, electrically connected to acommunication circuit, an antenna, and the first electrically conductiveexternal surface of the battery; wherein the first surface area isgreater than the second surface area.
 2. The apparatus of claim 1,wherein the first electrically conductive external surface electricallyconnects to a cathode of a primary alkaline battery, and the secondelectrically conductive external surface electrically connects to ananode of a primary alkaline battery.
 3. The apparatus of claim 1,wherein a ground plane of the communication circuit electricallyconnects to the negative terminal of the battery.
 4. The apparatus ofclaim 1, wherein the antenna impedance matching circuit comprises abalun configured to convert, for a first communication frequency, aninput impedance of the impedance matching circuit to an output impedanceof the impedance matching circuit.
 5. The apparatus of claim 1, whereinan electrical length of the first electrically conductive externalsurface is greater than 0.25 of a wavelength of a signal transmitted bythe communication circuit into the antenna impedance matching circuit,and wherein the electrical length of the first electrically conductiveexternal surface is a physical length of the first electricallyconductive external surface multiplied by the ratio of (i) thepropagation time of the signal through the first electrically conductiveexternal surface to (ii) the propagation time of the signal in freespace over a distance equal to the physical length of the firstelectrically conductive external surface.
 6. The apparatus of claim 5,wherein the electrical length of the first electrically conductiveexternal surface is configured to minimize a reflected power from theantenna back into the antenna impedance matching circuit as a result ofthe communication circuit transmitting the signal.
 7. The apparatus ofclaim 1, wherein the antenna impedance matching circuit comprises atleast one of (i) a capacitor and (ii) an inductor, and wherein at leastone of (i) the capacitor and (ii) the inductor are electricallyconnected between the communication circuit and the positive terminal ofthe battery.
 8. The apparatus of claim 2, wherein the battery comprisesa primary alkaline battery.
 9. The apparatus of claim 4, wherein thebalun comprises a first winding and a second winding around a magneticferrite, wherein a first end of the first winding is electricallyconnected to the antenna, and a second end of the first winding iselectrically connected to the positive terminal of the battery.
 10. Theapparatus of claim 9, wherein a first end of the second winding iselectrically connected to the communication circuit, and wherein asecond end of the second winding is electrically connected to theantenna.
 11. A method, comprising: providing a positive terminal of abattery, comprising a first electrically conductive external surfacewith a first surface area; providing a negative terminal of a battery,comprising a second electrically conductive external surface with asecond surface area less than the first surface area; providing anantenna impedance matching circuit; and electrically connecting theantenna impedance matching circuit to the positive terminal of thebattery.
 12. The method of claim 11, comprising electrically connectingthe antenna impedance matching circuit to a communication circuit and anantenna.
 13. The method of claim 12, comprising electrically connectinga ground plane of the communication circuit to the negative terminal ofthe battery.
 14. The method of claim 12, comprising providing a balunconfigured to convert an input impedance encountered by a signaltransmitted by the communication circuit into the impedance matchingcircuit to an output impedance.
 15. The method of claim 12, comprisingproviding the first electrically conductive external surface with anelectrical length greater than 0.25 of a wavelength of a signaltransmitted by the communication circuit into the antenna impedancematching circuit.
 16. The method of claim 15, comprising providing thefirst electrically conductive external surface with an electrical lengththat minimizes a reflected power from the antenna back into the antennaimpedance matching circuit as a result of the communication circuittransmitting the signal.
 17. The method of claim 11, comprisingproviding the antenna impedance matching circuit with at least one of(i) a capacitor and (ii) an inductor, and electrically connecting atleast one of (i) the capacitor and (ii) the inductor between acommunication circuit and the positive terminal of the battery.
 18. Themethod of claim 11, comprising: providing a primary alkaline battery;electrically connecting a cathode of the primary alkaline battery to ametal battery can; and electrically connecting the antenna impedancematching circuit to the cathode of the primary alkaline battery.
 19. Themethod of claim 12, comprising: providing a balun comprising a firstwinding and a second winding around a magnetic ferrite such that anoutput impedance of the balun approximates an input impedance of theantenna; electrically connecting a first end of the first winding to theantenna; and electrically connecting a second end of the first windingto the positive terminal of the battery.
 20. The method of claim 19,comprising: electrically connecting a first end of the second winding tothe communication circuit; and electrically connecting a second end ofthe second winding to the antenna.
 21. A method, comprising: providing anegative terminal of a primary alkaline battery, comprising a firstsurface area; providing a positive terminal of a primary alkalinebattery as a ground plane of an antenna, comprising a second surfacearea greater than the first surface area; providing an antenna impedancematching circuit; electrically connecting the antenna impedance matchingcircuit to the positive terminal of the battery; electrically connectingthe antenna impedance matching circuit to a communication circuit and anantenna; and calculating data relating to the remaining capacity of thebattery including corrections for load on the battery related totransmission and reception of data using the communication circuit, theantenna impedance matching circuit, the antenna, and the positiveterminal of the primary alkaline battery.
 22. The method of claim 21,comprising: transmitting the data relating to the remaining capacity ofthe primary alkaline battery using the communication circuit, theimpedance matching circuit, the antenna, and the positive terminal ofthe primary alkaline battery.
 23. The method of claim 22, comprising:transmitting the data relating to the remaining capacity of the batterywith a first effective radiated power of the antenna using the positiveterminal of the primary alkaline battery as the ground plane of theantenna while drawing a first current from the primary alkaline battery,wherein a second effective radiated power of the antenna comprises theeffective radiated power of the antenna using the negative terminal ofthe primary alkaline battery as a ground plane of the antenna whiledrawing the first current from the primary alkaline battery, and whereinthe first effective radiated power of the antenna is at least two timesthe second effective radiated power of the antenna.
 24. The method ofclaim 22, comprising: transmitting the data relating to the remainingcapacity of the primary alkaline battery with a first effective radiatedpower of the antenna using the positive terminal of the primary alkalinebattery as the ground plane of the antenna while drawing a first currentfrom the primary alkaline battery, wherein a second effective radiatedpower of the antenna comprises the effective radiated power of theantenna using the negative terminal of the primary alkaline battery as aground plane of the antenna while drawing a second current from theprimary alkaline battery, and wherein the first effective radiated powerof the antenna is equivalent to the second effective radiated power ofthe antenna, and the second current is greater than the first current.25. The method of claim 23, comprising: receiving the data transmittedat the first effective radiated power of the antenna with a reader at adistance greater from the antenna than if the data were transmitted withthe second effective radiated power of the antenna.